Process for treating textiles



Unite ical Company, Chicago, 11]., a corporation of Delaware No Drawing.FiledJune 25, 1959, Ser. No. 822,736 14 Claims. (Cl. 8-4163) Thisinvention relates to a method of chemically treating cellulose fabricsto improve their wash and wear characteristics. Specifically theinvention deals with a process for treating cotton fabrics whereby thetreated cotton is rendered crease-resistant.

For the past several years, intensive research has been conducted in anattempt to find chemical treatments for cellulose fabrics, particularlycotton cloths, which will impart to the fabric properties of creaseresistance. The ultimate object of such treatments is to obtain a fabricwhich, on being formed into a garment and being laundered, will have theinherent characteristics of drip-drying without forming wrinkles of thetype which are commonly removed by conventional ironing techniques.There have ben several attempts to impart to cellulose fabrics thesequalities by using amine formaldehyde resins and cyclic ureaformaldehyde resins. While these treatments have providedwrinkle-resistant characteristics to cotton fabrics, they impart to thecellulose fiber certain disadvantages which make their use not entirelysatisfactory from a commercial standpoint.

One of the chief drawbacks to the amine or urea type wrinkle-resistantresin treatments is that as the amount of resin placed into the fabricis increased, the fabrics tend to rapidly degrade upon being subjectedtolaundry chlorine bleaches. This chlorine bleach degradation phenomenonmay be mitigated to some extent by decreasing the amount of resin usedto treat the fabric. As the chlorine degradation phenomenon isdiminished by lowering the amount of resin placed into the fabric, therealso occurs a lessening in'the wrinkle-resistant characteristics. It,therefore, becomes necessary to critically adjust the amount oftreatment to balance the wrinkle-resistance against the bleachsusceptibility of the fabric.

Another disadvantage of many resin-treated cellulose fabrics is that thescorching characteristics of the fiber are such that the fabric willtend to yellow upon ironing. While ironing is not considered a necessityin truly wrinkle-resistant fabrics, many users of such fabrics find itnecessary to use occasional ironing procedures for so called touch-upjobs to improve the appearance of a particular garment.

'One of the reasons advanced for the inadequacies of the prior artmaterials is that they do not sufficiently react with the fiber wherebyan integral fiber resin bond is established in the form of athree-dimensional cross-linked network. Furthermore, there is aprogressive breakdown of these compounds on continued laundering.

It would be beneficial if a simple chemical treatment for cellulosefabrics were available which would impart a high degree ofcrease-resistance to fabrics at low, economical dosages, yet would notpossess the disadvantages of prior art treatments. Such a treatmentshould be simple operational techniques. ltalso should be capable atentof chemically combining with the cellulose molecule at a plurality ofpoints thereby forming an integral three- CAUST'IC TREATMENT In thisphase of the treatment the cellulose fabric is subjected to an aqueousbath which contains a minimum of at least 5% by weight of an alkalimetal hydroxide. While sodium, potassium, lithium, cesium, and rubidiumhydroxides may be used, from a commercial standpoint sodium hydroxide ispreferred since it gives good results in the process and is relativelyinexpensive. While the concentrations of the bath should be at least 5%by weight, it is advantageous to use between 5% and 20% by weightsolutions, with 10% solutions giving the optimum results. The bath maybe maintained at room temperature, viz. 7 2i5 F. Alternatively, it maybe elevated to higher temperatures such as about 210 F, depending uponthe type of operation sought to be achieved. The contact time of thecellulose fiber with the bath may vary from as littletime as 0.5 minuteto 5.0 minutes, depending upon the concentration of the caustic and thetemperature of the bath. ifshirt grade cotton'should be treated and a 10% caustic solution is to be used at room temperature, a typical,contact time would be about 2.0 minutes.

The purpose of this step is to convert a portion of the hydroxyl groupsin the cellulose molecule to the alkali metal alcoholate form, which ismore commonly known as sodium cellulose. After the fabric has beenconverted to the sodium form, it is then preferably padded to remove theexcess moisture from the cloth. At this point the fabric is then readyfor the second step, which I prefer to call etherization.

ETHERIZATION The padded alkali cellulose fabric is now immersed in anaqueous bath or solution which contains at least 1% by weight of awater-soluble acrylamide compound. The concentration of the :acrylamidecompound in this bath may be varied from a l% by weight concentration upto the saturation solubility of the particular acrylamide compound used.Commercial expediency suggests as a use ful range of concentrationbetween 2% and 5% by weight solution, with 2% being the most preferred.

The particular acrylamides that are used in the invention must beWater-soluble at use concentrations and they must contain at least onefree amido hydrogen. To more clearly illustrate compounds of this type,the following structural formula is presented:

In the above formula 'R maybe a radical selected from such groupings ashydrogen, methyl, ethyl, or propyl. R is a radical that may be eitherhydrogen, methyl, ethyl, propyl, butyl, isobutyl, or isopropyl; with, inthe above formula, at least one occurrence of R, being hydrogen.

Acrylamide N-methyl acrylamide ECHzOH Methacrylamide 2,3-dimethylbuten-2-y1 amide Z-methyl penten-2-yl amide HHOHCH:

l CH3 N-t-hutyl acrylamide N-methyl,2-ethyl acrylamide CHaH O HN-methyL3-methyl buten-2-yl amide 9 O O H l Penten-2y1 amide N-ethylmethacrylamide Of the above compounds by far the most preferred materialis acryl'arnide itself.

' As in the case of the alkali metal hydroxide bath, the

3 acrylamide bath may be used at about room temperature the particulartemperature employed. Here, as in the case of the caustic bath, the moreconcentrated the solution and the higher the temperature, the shorterwill be the contact time of the fabric being treated. In a typicalembodiment'of the invention, the fabricwould be im-- mersed in the 2%acrylamide solution at 75 F. for a period of about 2.0 minutes.

What is believed to have particular treatment step is to chemically linkthe acrylamide through the vinyl linkage to the cellulose moleculethrough the chemical process of what might be described as etherization.For purposes of illustrating what is hebeen accomplished in this lievedto be the mechanism ture is presented:

OHtOCHflCHzC-NHE II o H H l L T l H H0 7 n The above represents asegment of a cellulose chain showing the linkage of monomericacrylamide. It will be understood that the above is presented forpurposes of a clearer understanding of the invention, and it is notintended that the above is binding insofar as it relates to the inherentmode by which the invention operates.

Once again the fabric would be preferably padded to remove the excessliquid and the fabric would then be ready for the final treatingprocess, which bath contains an acidic reagent and certain portions offormaldehyde.

ACIDIC FORMALDEHYDE TREATMENT The padded fabric is immersed into ortreated with an acidic aqueous solution of formaldehyde. The amount offormaldehyde contained in this bath is adjusted in proportion to theamount of acrylamide contained in the acrylamide bath, so that the molarratio of formaldehyde to water-soluble acrylamide is at least 3:1. Themol-ar ratio may be varied over a considerable range whereby ratios ashigh as 5:1 may be employed, although from an eco- V nomic standpointthe molar ratio of the formaldehyde to water-soluble acry-lamide ispreferably maintained the range of 3:1 to 4:1. The pH of theformaldehyde bath is adjusted with an acidic reagent to produce a pHwithin the range of 2.0 to 7.0. Preferably the pH is maintained withinthe range of 4.5 to 6.5.

The concentration of the acidic reagent may be varied over wide rangeswhich, of course, are dependent upon the pH range. The usual weightrange of the acidic reagent is between 5% and 10% by weight. The acidityof the formaldehyde bath causes the amide grouping of the water-solubleacrylamide to react with the formaldehyde to form at least one methylolderivative. The acid 45 reagent is also present in the bath to causesubsequent cross-linking of the methylol amide groups, which. mechanismwill be described more fully hereinafter.

The number of acidic reagents which may be used may be selected from alarge number of chemical compounds of either the organic or inorganicype. Since the particular acidic material used is not critical, it isbelieved that any number of compounds may be used without departing fromthe spirit of the invention. For purposes of illustration, however, thefollowing partial list of acidic compounds is presented: phosphoricacid, zinc sulfate,

zinc nitrate, zinc chloride, magnesium chloride, triethylaminehydrochloride, citric acid, tartaric acid, and the well- 7 known strongmineral acids, hydrochloric and sulfuric. In the case of the strongmineral acids, alkaline buffering agents are used so that better pHcontrol is maintained.

The temperature of the acidic formaldehyde treating bath may be variedfrom about room temperature to higher temperatures, although care mustbe exercised in order not to lose the formaldehyde by the use ofexcessive heat. The contact time of, the treated fabric with the acidicform-aldehyde bath will vary from 1.0 minute to 5.0 minutes, dependingupon the concentrations and temperatures employed. A 5% formaldehydesolution, having a pH of 5.5 at room temperature, would be in contactwith the treated fabric for 2.0 minutes in a typical embodiment of theinvention.

CROSS-LINKING After the fabric has been treated in the acidicformaldehyde bath, it is then subjected to a curing or heat treatmentinvolved, the following strucstep which further reacts the methylolamide fabric linkage with the free hydroxyl position-s of the celluloseto form a three-dimensional cross-linked network. A simplifiedillustration of this cross linking phenomenon is presented below:

I-O "I O 3/4 r no \ii V' 6 of the invention. All the test baths weremaintained at temperatures of 72:5 F. The contact time of the fabricwith each bath was approximately 2.0 minutes. Between each bath thefabrics were padded on a hand laundry roller which exerted anapproximate pressure of 40 pounds CHaOH CHzOH CHrOH g CHzOH per squareinch. The fabric leaving the roller was slightly damp to the touch. Thetreated fabrics were tested for their crease-resistant properties on theMonsanto Wrinkle Recovery Tester, which is 'describedin the TechnicalManual and Yearbook of the American Association of Textile Chemists andColorists, vol. 32, 1956 (Tentative Test Method 66-56). v i

The chlorine retention properties of the treated and untreated fabricswere determined in accordance with AATCC tentative test method 69-52,which is described Table II in the Technical Manual and Yearbook of theAmerican Temperature in C.: Time in minutes Association of TextileChemists and Colorists, vol. 28,

9 1952. 6 The padded fabric used in the tests was a commercial 1 60 4grade of unbleached shirt type cotton lawn having an 17-0 2 80 x 80weave. 1 50 e results of thesetests are presented below in Table 0.4III:

Table III Acryl- Percent Molar rati 1 Percent amide acryl- Percent HOHO'1 Warp Fill 'Test No. NaOl-I cornamide ECHO Acrylamide Catalyst pH angleangle pound 1 corncompound average 2 average 2 pound 7.5 68(4) 66(4) 1 25.5 0.5 Zn(NO3)z 3.5 78(4) 77(4 1 4 i 5.5 3.3 ZH(NO3)2 3.5" 75(4) 76 410 .1 2 5.5 6.5 Zn(NOs)z 3.5 137(4) 140(4 10 3 2 5.5 7.8 MgClz 4.8125(4) 129(4 5 1 2 5.5 6.5 211012 5.3 143(2) 132 2 5 1 1 3.0 3.3Zn(NOa)2 3.8 143 3) 141(3) 10 1 1 3.0 3.3 Zn(NOs)1 3.8 142 1) 126 1 10 12 1.0 1.2 Zn(NOa)2- 3 .8 69 4 39 4) 1 1 0.5 3.0 1.6 Zn(NO3)2 3.5 83(337(3) 10 6 2 6.0 1 7.0 Zn(N01) 3.8 132(4) 128(4) 1 See Table I.

2 Figure in brackets is numberof tests run.

. EVALUATION OF THE INVENTION By using the general procedures outlinedabove, the following tests were conducted to demonstrate the efficacyThe above fabrics treated in accordance with the invention showed nodegradation nor appreciable chlorine pick-up. Additionally, thepreferred treated fabrics of the 'I'hcfinished product of the inventionmay be considered 7 as a cellulose fabric containing from .5% to 3 byweight of a cured acrylamide formaldehyde copolymer which is chemicallybonded to the fabric through a plurality of ether linkages. The amountsof formaldehyde combined with acrylamide in a finished cotton co'polymercombination may be expressed in terms of a formaldehydeacrylamide molarratio of at least 1:1. 'It will be apparent by studying the variousstructural formulas that the amount of formaldehyde which combines withthe acrylamide molecule will be somewhat less than the quantity used inthe treating bath. The excess of formaldehyde used in the bath probablyacts as a driving force to make the reaction go to completion morereadily under the conditions used. The amounts of formaldehyde in thebath specified are critical, and lesser amounts afiford poor results.

The cfinished'fabrics' of the invention, in addition to having thewrinkle-resistant finish imparted to them, also have several otherproperties which are not achieved by use of prior art materials. In thecase of white goods, the wearing quality of the cloth is in no waydiminished and in some instances it is improved, and bleached fabricshave improved whiteness. Since several improved properties are impartedto the fabric, I prefer to term my treated fabrics as having improvedshape-holding qualities,

which term is intended to mean that the fabric has all or. several ofthe above qualities in addition to that of wrinkle-resistance.

While the invention is primarily concerned with treating cellulosefabrics which are composed exclusively of cotton, it will be apparentthat .the invention applies to fabrics which are blends of cellulosefibers and synthetic or modified fibers. The invention therefore isdesigned to treat cotton-containing fabrics which contain at least 40%by weight of cotton fibers. Such fibers as cellulose acetates of therayon type, nylon polyamide type fibers, polyester fibers, vinylacetate, acrylonitrile fibers, vinyline chloride, vinyl chloride,copolymers of acrylonitrile, vinylidene cyanide, and other, vinylmonomers may all be suitably blended with cotton which, when treated inaccordance with the invention, will show improved results.

It will also be apparent to those skilled in theart that the inventionmay be advantageously combined with other textile treatments andreagents, such as softening and bleaching agents, to combine theireffects and reduce the amount of processing equipment necessary toproduce a suitable fabric. When used in conjunction with softeningreagents, it is preferred to use the saturated di-fattyquaternary'ammonium compounds of which dioctadecyl-diethylammoniumchloride is exemplary. Another useful group of fatty-containing textilesofteners are those described in Johnson U.S. Patent 2,874,074.

The invention is hereby claimed as follows:

1. The process of treating cellulose fabrics to improve their shapeholding qualities which comprises the sequential steps of contactingsaid fabrics with an aqueous bath containing from 5% to 20% by weight ofsodium hydroxide, contacting the alkali-treated fabric with an aqueoussolution containing from 1% to the saturation solubility of anacrylamide of the formula:

R R 0 R1 I I ll RC=OC-N where R is from the group consisting ofhydrogen, methyl,

8 and ethyl, and R is from the group consisting of hydrogen, methyl,ethyl, propyl, isopropyl, butyl, and isobutyl, with the proviso that atleast one occurrence of R is hydrogen, and then subjecting theacrylamide treated fabric to. an aqueous acidic bath which contains anamount of formaldehyde calculated to give a formaldehyde towater-soluble acrylamide molar ratio of from 3:1 to 4:1, said bathcontaining from 3% to 10% by weight of water soluble chemical whichgives said bath a pH of from 4.5 to 6.5, and finally curing the treatedfabric at a temperature between C. to C.

2. The proceess of claim 1 where the cellulose fabric is predominantlygarment grade cot-ton, the sodium hydroxide bath has a concentration offrom 5% to 10% by weight and the water-soluble acrylamide is acrylamide.

3. The process of treatingcellulose fabrics to improve theirshape-holding qualities which comprises the sequential steps ofcontacting said fabrics with an aqueous bath containing from 5% to 20%by weight of an alkali metal hydroxide, contacting the alkali-treatedfabric with an aqueous bath which contains from at least 1% by weight tothe saturation solubility of a water soluble acrylamide compound, saidacrylamide compound containing at least 1 reactive amido hydrogen, thencontacting the acrylamide compound-treated fabric with an aqueous acidicbath which contains an amount of formaldehyde calculated to give aformaldehyde to water-soluble acrylamide compound molar ratio of atleast 3:1, with the pH of said bath having been adjusted within therange of from v 2 to 7, by the addition of a water soluble acidicreagent,

and finally curing the treated fabric at a temperature between 140 C.and C.

7. The process in accordance with claim 3 where the acrylamide compoundis methacrylamide.

8. The process of claim 3 where the acrylamide compound is N-t-butylacrylamide.

9. The process of treating of cellulose fabrics to improve'theirshape-holding qualities which comprises the sequential steps ofcontacting said fabrics with an aqueous bath containing from '5 to 20%by weight of an alkali metal hydroxide, contacting the alkali-treatedfabric with an aqueous solution containing frombetween 1% to 5% byweight of an acrylamide compound from the group consisting ofacrylamide, methacrylamide, and N-t-butyl acrylamide, and thencontacting the acrylamide compound treated fabric with an aqueous acidicbath which contains an amount of formaldehyde calculated to give aformaldehyde to acrylamide compound molar ratio of from 3:1 to 4:1, saidbathcontaining a suflicient quantity of an acidic salt from the groupconsisting of the acidic salts of'zinc and magnesium to adjust the pH ofsaid bath to between the ranges of from 4.5 to 6.5, and finally 9 11.The cellulose fabric of claim 10 Where the starting acrylamide compoundhas the formula:

R? Br where R is a member of the class from the group consisting ofhydrogen, methyl, and ethyl and R is from the group consisting ofhydrogen, methyl, ethyl, butyl, isobutyl, propyl, and isopropyl, withthe proviso that at least one occurrence of R is hydrogen.

12. The cellulose fabric of claim 11 where the sequentially reactedacrylamide-formaldehyde product was formed from acrylamide.

13. The cellulose fabric of claim 11 where the sequentially reactedacrylamide-formaldehyde reaction product was formed from methacrylamide.

14. The cellulose fabric of claim 11 where the sequen- 2,173,005 Strain1 Sept. 12, 1939 2,338,681 Bock Jan. 4, 1944 2,837,512 Mantell June 3,1958 2,966,481 Brace Dec. 27, 1960 2,971,815 Bullock Feb. 14, 1961 OTHERREFERENCES Matlin, Industrial and Engineering Chemistry, vol. 47, No. 9,September 1955, pages 1729-1730.

Prick, Textile Research Journal, vol. XPGX, No. 4, April 1959, pages314322.

Kress, American Dyestuff Reporter, vol. 48, No. 4, Feb. 23, 1959, page33.

1. THE PROCESS OF TREATING CELLULOSE FABRICS TO IMPROVE THEIR SHAPEHOLDING QUALITIES WHICH COMPRISES THE SEQUENTIAL STEPS OF CONTACTINGSAID FABRICS WITH AN AQUEOUS BATH CONTAINING FROM 5% TO 20% BY WEIGHT OFSODIUM HYDROXIDE, CONTACTING THE ALKALI-TREATED FABRIC WITH AN AQUEOUSSOLUTION CONTAINING FROM 1% TO THE SATURATION SOLUBILITY OF ANACRYLAMIDE OF THE FORMULA: